Incredible! I know some people who will love this. :D
I had to re-read the controls to realize the mouse pointer's location was important, I kept swatting the same plant up and down uselessly at first. The third level was tough, but mostly because I'm too impatient.
Very lucky that the distracted human can't hear any of these things landing on the floor. :) Though, it might be nice from the player's perspective to hear a satisfying crash or two!